The CIDS trial was a secondary prevention trial in 659 patients after resuscitated VF or VT or with unmonitored syncope, randomly assigned to treatment with an ICD or with amiodarone. It showed a 20% relative risk reduction with ICD therapy in all-cause mortality and a 33% reduction in arrhythmic mortality compared with amiodarone but these reductions did not reach statistical significance

The CASH-trial was the third secondary prevention trial that showed that ICD therapy in cardiac arrest survivors is associated with a 23% (albeit nonsignificant) reduction of all-cause mortality rates when compared with treatment with amiodarone or metoprolol. Of note, an initial propafenone arm of the study was prematurely discontinued after an interim analysis showed a 61% higher all-cause mortality rate than in ICD patients.Improved survival with an implanted defibrillator in patients with coronary disease at high risk for ventricular arrhythmia. Multicenter Automatic Defibrillator Implantation Trial Investigators.

Original MADIT-trial. Although a small trial (196 post-MI patients with an LVEF of ≤35%) it opened the era of prophylactic ICD implantations to protect patients without prior sudden death or sustained VT against sudden death. It concluded that in patients with a prior MI who are at high risk for ventricular tachyarrhythmia, prophylactic ICD therapy leads to improved survival as compared with conventional medical therapy.A randomized study of the prevention of sudden death in patients with coronary artery disease. Multicenter Unsustained Tachycardia Trial Investigators. Buxton AE, Lee KL, Fisher JD, Josephson ME, Prystowsky EN, Hafley G. N Engl J Med 1999;341:1882-1890.

The DINAMIT trial showed that prophylactic ICD therapy 6 to 40 days after a myocardial infarction in patients with an LVEF of ≤35% and depressed heart-rate variability or an elevated average 24-hour heart rate, did not reduce overall mortality. Although ICD therapy was associated with a reduction in the rate of death due to arrhythmia, that was offset by an increase in the rate of death from nonarrhythmic causes

The moderately sized DEFINITE trial, which randomized 458 patients with nonischemic dilated cardiomyopathy and a LVEF of ≤35% (and frequent VPB or nonsustained VT) to medical therapy alone or with the addition of a VVI-ICD, just failed to reach statistical significance to show a reduction in the risk of death from any cause.

Cost-effectiveness (C/E) calculations based on prospectively collected data of the patients in the AVID trial, the first randomised secondary prevention trial. The base-case C/E ratio was $66 677 per year of life saved by the ICD compared with AAD therapy (95% CI, $30 761 to $154 768). Six- and 20-year C/E ratios remained stable between $68 000 and $80 000 per year of life saved. The ICD is moderately cost-effective for secondary prevention of life-threatening ventricular arrhythmias.Addendum to "Personal and Public Safety Issues Related to Arrhythmias That May Affect Consciousness: Implications for Regulation and Physician Recommendations: A Medical/ Scientific Statement From the American Heart Association and the North American Society of Pacing and Electrophysiology." Public Safety Issues in Patients With Implantable Defibrillators. A Scientific Statement From the American Heart Association and the Heart Rhythm Society. Epstein AE, Baessler CA, Curtis AB, Estes NA 3rd, Gersh BJ, Grubb B, Mitchell LB Circulation 2007;115:1170-1176.

Extension of the original recommendations concerning driving with ICD from 1996, in which driving for patients with ICDs implanted for primary prevention was briefly discussed. It is now recommended that they should be restricted from driving a private automobile for at least 1 week to allow for recovery from implantation of the defibrillator. Thereafter, these driving privileges should not be restricted in the absence of symptoms potentially related to an arrhythmia. If they subsequently receive an appropriate therapy, especially with symptoms of cerebral hypoperfusion, they should be considered to be subject to the driving guidelines previously published for patients who received an ICD for secondary prevention.Sudden cardiac arrest associated with early repolarization. Haissaguerre M, Derval N, Sacher F, Jesel L, Deisenhofer I, de Roy L, Pasquie JL, Nogami A, Babuty D, Yli-Mayry S, De Chillou C, Scanu P, Mabo P, Matsuo S, Probst V, Le Scouarnec S, Defaye P, Schlaepfer J, Rostock T, Lacroix D, Lamaison D, Lavergne T, Aizawa Y, Englund A, Anselme F, O'Neill M, Hocini M, Lim KT, Knecht S, Veenhuyzen GD, Bordachar P, Chauvin M, Jais P, Coureau G, Chene G, Klein GJ, Clementy J. N Engl J Med 2008;358:2016-2023.

This multicenter report describing 206 case subjects at 22 centers describes for the first time the association between a new QRS-ST junction variant and malignant ventricular arrhythmias. The variant was defined as an elevation of the QRS-ST junction of at least 0.1 mV from baseline in the inferior or lateral lead, manifested as QRS slurring or notching. The variant was significantly more frequent in case subjects with idiopathic VF than in 406 matched control subjects (31% vs. 5%, P<0.001). Cases were more often male and and had a history of syncope or sudden cardiac arrest during sleep. Moreover, ICD patients with a repolarization abnormality more often had recurrent VF than those without such an abnormality (HR 2.1; P=0.008).

Of particular importance in health-economic evaluations of ICD therapy is whether ICD treatment is accompanied by deterioration in the quality of life (QOL) is unclear. QOL was prospectively measured in 2521 SCD-HeFT patients at months 3, 12, and 30. Psychological well-being in the ICD group, as compared with medical therapy alone, was significantly improved at 3 months (P=0.01) and at 12 months (P=0.003) but not at 30 months. No clinically or statistically significant differences in physical functioning among the study groups were observed. ICD shocks in the month preceding a scheduled assessment were associated with a decreased quality of life in multiple domains. The use of amiodarone had no significant effects on the primary quality-of-life outcomes. Therefore, the authors conclude that single-lead ICD therapy was not associated with any detectable adverse quality-of-life effects during 30 months of follow-up.